1,265 research outputs found
Solutions for 10,000 Eclipsing Binaries in the Bulge Fields of OGLE II Using DEBiL
We have developed a fully-automated pipeline for systematically identifying
and analyzing eclipsing binaries within large datasets of light curves. The
pipeline is made up of multiple tiers which subject the light curves to
increasing levels of scrutiny. After each tier, light curves that did not
conform to a given criteria were filtered out of the pipeline, reducing the
load on the following, more computationally intensive tiers. As a central
component of the pipeline, we created the fully automated Detached Eclipsing
Binary Light curve fitter (DEBiL), which rapidly fits large numbers of light
curves to a simple model. Using the results of DEBiL, light curves of interest
can be flagged for follow-up analysis. As a test case, we analyzed the 218699
light curves within the bulge fields of the OGLE II survey and produced 10862
model fits. We point out a small number of extreme examples as well as
unexpected structure found in several of the population distributions. We
expect this approach to become increasingly important as light curve datasets
continue growing in both size and number.Comment: Accepted for publication in ApJ, 36 pages, 15 figures, 5 tables. See
http://cfa-www.harvard.edu/~jdevor/DEBiL.html for high-resolution figures and
further informatio
First search for gravitational waves from the youngest known neutron star
We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia
A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser
Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz
and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and
for different spin-down mechanisms. No gravitational-wave signal was detected. Within the range of search
frequencies, we set 95% confidence upper limits of (0.7–1.2) × 10^(−24) on the intrinsic gravitational-wave
strain, (0.4–4) × 10^(−4) on the equatorial ellipticity of the neutron star, and 0.005–0.14 on the amplitude of
r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy
conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes.
This paper is also the first gravitational-wave search to present upper limits on the r-mode amplitude
Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - IV. A 0.61 + 0.45 M_sun binary in a multiple system
We present the orbital and physical parameters of a newly discovered low-mass
detached eclipsing binary from the All-Sky Automated Survey (ASAS) database:
ASAS J011328-3821.1 A - a member of a visual binary system with the secondary
component separated by about 1.4 seconds of arc. The radial velocities were
calculated from the high-resolution spectra obtained with the 1.9-m
Radcliffe/GIRAFFE, 3.9-m AAT/UCLES and 3.0-m Shane/HamSpec
telescopes/spectrographs on the basis of the TODCOR technique and positions of
H_alpha emission lines. For the analysis we used V and I band photometry
obtained with the 1.0-m Elizabeth and robotic 0.41-m PROMPT telescopes,
supplemented with the publicly available ASAS light curve of the system.
We found that ASAS J011328-3821.1 A is composed of two late-type dwarfs
having masses of M_1 = 0.612 +/- 0.030 M_sun, M_2 = 0.445 +/- 0.019 M_sun and
radii of R_1 = 0.596 +/- 0.020 R_sun, R_2 = 0.445 +/- 0.024 R_sun, both show a
substantial level of activity, which manifests in strong H_alpha and H_beta
emission and the presence of cool spots. The influence of the third light on
the eclipsing pair properties was also evaluated and the photometric properties
of the component B were derived. Comparison with several popular stellar
evolution models shows that the system is on its main sequence evolution stage
and probably is more metal rich than the Sun. We also found several clues which
suggest that the component B itself is a binary composed of two nearly
identical ~0.5 M_sun stars.Comment: 12 pages, 7 figures, 7 tables, to appear in MNRA
High-precision photometry by telescope defocussing. III. The transiting planetary system WASP-2
We present high-precision photometry of three transits of the extrasolar
planetary system WASP-2, obtained by defocussing the telescope, and achieving
point-to-point scatters of between 0.42 and 0.73 mmag. These data are modelled
using the JKTEBOP code, and taking into account the light from the
recently-discovered faint star close to the system. The physical properties of
the WASP-2 system are derived using tabulated predictions from five different
sets of stellar evolutionary models, allowing both statistical and systematic
errorbars to be specified. We find the mass and radius of the planet to be M_b
= 0.847 +/- 0.038 +/- 0.024 Mjup and R_b = 1.044 +/- 0.029 +/- 0.015 Rjup. It
has a low equilibrium temperature of 1280 +/- 21 K, in agreement with a recent
finding that it does not have an atmospheric temperature inversion. The first
of our transit datasets has a scatter of only 0.42 mmag with respect to the
best-fitting light curve model, which to our knowledge is a record for
ground-based observations of a transiting extrasolar planet.Comment: Accepted for publication in MNRAS. 9 pages, 3 figures, 10 table
Search for Gravitational-wave Inspiral Signals Associated with Short Gamma-ray Bursts During LIGO's Fifth and Virgo's First Science Run
Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [ – 5, + 1) s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U-test, we find no evidence for an excess of weak gravitational-wave signals in our sample of GRBs. We exclude neutron star-black hole progenitors to a median 90% confidence exclusion distance of 6.7 Mpc
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